Analysis of Magnetorheological Fluid Brake System and its Operation

The MR brake consists of multiple rotating disks immersed into an MR fluid and an enclosed electromagnet. When current is applied to the electromagnet coil, the MR fluid solidifies as its yield stress varies as a function of the magnetic field applied by the electromagnet. This controllable yield stress produces shear friction on the rotating disks, generating the braking torque. This type of braking system has the following advantages: faster response, easy implementation of a new controller or existing controllers (e.g. ABS, VSC, EPB, etc.), less maintenance requirements since there is no material wear and lighter overall weight since it does not require the auxiliary components used in CHBs. The MRB design process included several critical design steps such as the magnetic circuit design and material selection as well as other practical considerations such as cooling and sealing. A basic MRB configuration was selected among possible candidates and a detailed design was obtained according to a set of design criteria. Then, with the help of a finite element model (FEM) of the MRB design, the magnetic field intensity distribution within the brake was simulated and the results were used to calculate the braking torque generation.

D. G. FERNANDO: Characterizing the behaviour of magnetorheological fluids at high velocities and high shear rates, PhD thesis, Faculty of the Virginia Polytechnic Institute and state University, Blacksburg, Virginia (2005).

K. KARAKOC: Design of a Magnetorheological Brake System Based on Magnetic Circuit Optimization, PhD Thesis, Department of Mechanical Engineering, University of Victoria, Victoria, Canada (2007).